a person in a coma: what can be done?life support or euthanasia?

..this has been a subject of debate ever since.. well, for me, it already depends on the people concerned.. of course in my own opinion, I'd say that no one has the right to take away life even if it is mercy killing because only God knows when the right time for a person to die has come or not.. we never knew God's plan.. but others who feel tired of watching their loved ones being unconscious for how many months or years feel pity towards their loved ones.. the more they say their loved ones in the coma situation, the more they feel hurt.. this is why others turn to mercy killing.. I can't blame them though i won;t say that I agree with them too.. It's just that, we have our own reasons and maybe, God somehow understands..